1. Field of the Invention
The invention relates generally to the field of orthodontics and, more particularly, to computer-automated development of an orthodontic treatment plan and appliance.
2. Description of the Background Art
Repositioning teeth for aesthetic or other reasons is accomplished conventionally by wearing what are commonly referred to as xe2x80x9cbraces.xe2x80x9d Braces comprise a variety of appliances such as brackets, archwires, ligatures, and O-rings. Attaching the appliances to a patient""s teeth is a tedious and time-consuming enterprise requiring many meetings with the treating orthodontist. Consequently, conventional orthodontic treatment limits an orthodontist""s patient capacity and makes orthodontic treatment quite expensive. As such, the use of conventional braces is a tedious and time consuming process and requires many visits to the orthodontist""s office. Moreover, from the patient""s perspective, the use of braces is unsightly, uncomfortable, presents a risk of infection, and makes brushing, flossing, and other dental hygiene procedures difficult.
Tooth positioners for finishing orthodontic treatment are described by Kesling in the Am. J. Orthod. Oral. Surg. 31:297-304 (1945) and 32:285-293 (1946). The use of silicone positioners for the comprehensive orthodontic realignment of a patient""s teeth is described in Warunek et al. (1989) J. Clin. Orthod. 23:694-700. Clear plastic retainers for finishing and maintaining tooth positions are commercially available from Raintree Essix, Inc., New Orleans, La. 70125, and Tru-Tain Plastics, Rochester, Minn. 55902. The manufacture of orthodontic positioners is described in U.S. Pat. Nos. 5,186,623; 5,059,118; 5,055,039; 5,035,613; 4,856,991; 4,798,534; and 4,755,139.
Other publications describing the fabrication and use of dental positioners include Kleemann and Janssen (1996) J. Clin. Orthodon. 30:673-680; Cureton (1996) J. Clin. Orthodon. 30:390-395; Chiappone (1980) J. Clin. Orthodon. 14:121-133; Shilliday (1971) Am. J. Orthodontics 59:596-599; Wells (1970) Am. J. Orthodontics 58:351-366; and Cottingham (1969) Am. J. Orthodontics 55:23-31.
Kuroda et al. (1996) Am. J. Orthodontics 110:365-369 describes a method for laser scanning a plaster dental cast to produce a digital image of the cast. See also U.S. Pat. No. 5,605,459.
U.S. Pat. Nos. 5,533,895; 5,474,448; 5,454,717; 5,447,432; 5,431,562; 5,395,238; 5,368,478; and 5,139,419, assigned to Ormco Corporation, describe methods for manipulating digital images of teeth for designing orthodontic appliances.
U.S. Pat. No. 5,011,405 describes a method for digitally imaging a tooth and determining optimum bracket positioning for orthodontic treatment. Laser scanning of a molded tooth to produce a three-dimensional model is described in U.S. Pat. No. 5,338,198. U.S. Pat. No. 5,452,219 describes a method for laser scanning a tooth model and milling a tooth mold. Digital computer manipulation of tooth contours is described in U.S. Pat. Nos. 5,607,305 and 5,587,912. Computerized digital imaging of the jaw is described in U.S. Pat. Nos. 5,342,202 and 5,340,309. Other patents of interest include U.S. Pat. Nos. 5,549,476; 5,382,164; 5,273,429; 4,936,862; 3,860,803; 3,660,900; 5,645,421; 5,055,039; 4,798,534; 4,856,991; 5,035,613; 5,059,118; 5,186,623; and 4,755,139.
In one aspect, a computer-implemented method to prepare a malocclusion treatment plan includes selecting a tooth treatment pattern from a library of predetermined tooth treatment patterns; and generating the malocclusion treatment plan implementing the selected tooth treatment pattern.
Implementations of the above aspect may include one or more of the following. The generating the malocclusion treatment plan includes determining one or more tooth paths based on the selected tooth treatment pattern. The treatment pattern can be selected from one or more clinical treatment prescriptions. The clinical treatment prescription includes at least one of the following: space closure, reproximation, dental expansion, flaring, distalization, and lower incisor extraction. The determining a tooth path includes finding a collision free shortest path between an initial position and a final position for one or more teeth. The generating the malocclusion treatment plan includes specifying a series of treatment stages for one or more teeth. The method can include dividing a path for one or more teeth into the series of stages while keeping the movement of teeth in each stage below a predetermined range. The method can include generating an appliance for each treatment stage. The appliance can be either a removable appliance or a fixed appliance. The method can include generating a three-dimensional model for the teeth for each treatment stage. The method also can include generating dental diagnostic information from the three-dimensional model. Interproximal reduction, tooth size discrepancy information, and Bolton information, among others can be generated from the 3D model. The library of treatment patterns includes at least one or more of the following: all equal movement pattern, A-shaped movement pattern, V-shaped movement pattern, M-shaped movement pattern, W-shaped movement pattern, symmetric staircase pattern, asymmetric staircase pattern, and equal equal movement pattern. For the all equal movement pattern, the method includes subdividing paths while satisfying one or more constraints. The constraint can be minimizing tooth oscillation and tooth movement distance. For the equal equal pattern, the method includes dividing the teeth into a prestage movement group and a post stage movement group; and applying the all equal movement to the prestage movement group and subsequently applying the all equal movement to the prestage movement group. For the A-shaped movement pattern, the method includes sequentially moving each tooth from an incisor tooth toward a molar tooth. For the V-shaped movement pattern, the method includes sequentially moving each tooth from a molar tooth toward an incisor tooth.
In another aspect, a computer-implemented method prepares a malocclusion treatment plan by: selecting one tooth treatment pattern from a library of predetermined tooth treatment patterns; generating the malocclusion treatment plan in accordance with the selected treatment pattern; and producing a plurality of data sets representing a series of successive tooth arrangements progressing from a first tooth arrangement to a second tooth arrangement. Implementations of this aspect may include generating an appliance for each tooth arrangement.
In another aspect, a computer-readable medium executable by a computer to prepare a malocclusion treatment plan includes code to select one tooth treatment pattern from a library of predetermined tooth treatment patterns; and code to generate the malocclusion treatment plan in accordance with the selected treatment pattern.
Implementation of this aspect may include one or more of the following. The medium can include code to fabricate an appliance for each tooth arrangement. The code to fabricate appliances can include code to control a fabrication machine to produce successive positive models of the tooth arrangements; and code to produce the appliance as a negative of the tooth model. The code to control a fabrication machine includes code to provide a volume of non-hardened polymeric resin; and code to scan a laser to selectively harden a resin to produce the positive model. The medium can include code to control a fabrication machine to produce successive appliances for the tooth arrangements.
In yet another aspect, a computer-implemented method to automatically stage a series of tooth movements, by selecting one teeth treatment pattern from a plurality of predetermined teeth treatment patterns; generating a treatment plan for the teeth in accordance with the selected move pattern by: generating a treatment plan with a tooth path for each tooth; and determining a series of treatment stages for the teeth; and controlling a fabrication machine to produce successive appliances for the tooth arrangements.
Implementations of this aspect may include generating an appliance as a negative or a positive of a dental model.
In another aspect, an appliance to correct malocclusion, the appliance formed using computer readable code controlling a fabrication machine, the code comprising instructions to: select one teeth treatment pattern from a plurality of predetermined teeth treatment patterns; generate a treatment plan for the teeth in accordance with the selected move pattern by: generate a treatment plan with a tooth path for each tooth; and determine a series of treatment stages for the teeth; and control the fabrication machine to produce successive appliances for the tooth arrangements.
In another aspect, a computer system to prepare a malocclusion treatment plan includes a processor; a display coupled to the processor; and a data storage device coupled to the processor and containing code to select a tooth treatment pattern from a library of predetermined tooth treatment patterns; and code to generate the malocclusion treatment plan implementing the selected tooth treatment pattern.
In yet another aspect, a computer system to prepare a malocclusion treatment plan includes means for selecting a tooth treatment pattern from a library of predetermined tooth treatment patterns; and means for generating the malocclusion treatment plan implementing the selected tooth treatment pattern.
Yet other implementations of the above aspects can include one or more of the following. The constraints relates to teeth crowding, teeth spacing, teeth extraction, teeth stripping, teeth rotation, and teeth movement. The teeth can be rotated approximately five and ten degrees (per stage) and can be incrementally moved in one or more stages (per stage), each stage moving each tooth approximately 0.2 mm to approximately 0.4 mm. The constraints can be stored in an array with one dimension of the array identifying each stage in the teeth movement. The treatment paths can include determining the minimum amount of transformation required to move each tooth from the initial position to the final position and creating each treatment path to require only the minimum amount of movement. Additionally, intermediate positions can be generated for at least one tooth between which the tooth undergoes translational movements of equal sizes. Further, intermediate positions can be generated for at least one tooth between which the tooth undergoes translational movements of unequal sizes. A set of rules can be applied to detect any collisions that will occur as the patient""s teeth move along the treatment paths. Collisions can be detected by calculating distances between a first tooth and a second tooth by establishing a neutral projection plane between the first tooth and the second tooth, establishing a z-axis that is normal to the plane and that has a positive direction and a negative direction from each of a set of base points on the projection plane, computing a pair of signed distances comprising a first signed distance to the first tooth and a second signed distance to the second tooth, the signed distances being measured on a line through the base points and parallel to the z-axis, and determining that a collision occurs if any of the pair of signed distances indicates a collision. Where the positive direction for the first distance is opposite the positive direction for the second distance, a collision is detected if the sum of any pair of signed distances is less than or equal to zero. Information indicating whether the patient""s teeth are following the treatment paths can be used to revise the treatment paths. More than one candidate treatment path for each tooth can be generated and graphically displayed for each candidate treatment path to a human user for selection. A set of rules can be applied to detect any collisions that will occur as the patient""s teeth move along the treatment paths. Collisions can be detected by calculating distances between a first tooth and a second tooth by: establishing a neutral projection plane between the first tooth and the second tooth, establishing a z-axis that is normal to the plane and that has a positive direction and a negative direction from each of a set of base points on the projection plane, computing a pair of signed distances comprising a first signed distance to the first tooth and a second signed distance to the second tooth, the signed distances being measured on a line through the base points and parallel to the z-axis, and determining that a collision occurs if any of the pair of signed distances indicates a collision. A collision can also be detected if the sum of any pair of signed distances is less than or equal to zero. A set of rules can be applied to detect any improper bite occlusions that will occur as the patient""s teeth move along the treatment paths. A value for a malocclusion index can be computed and the value displayed to a human user. The treatment paths can be generated by receiving data indicating restraints on movement of the patient""s teeth and applying the data to generate the treatment paths. A three-dimensional (3D) graphical representation of the teeth at the positions corresponding to a selected data set can be rendered. The graphical representation of the teeth to provide a visual display of the movement of the teeth along the treatment paths can be generated. A graphical interface, with components representing the control buttons on a videocassette recorder, which a human user can manipulate to control the animation, can be generated. A portion of the data in the selected data set may be used to render the graphical representation of the teeth. A level-of-detail compression can be applied to the data set to render the graphical representation of the teeth. A human user can modify the graphical representation of the teeth and the selected data set can be modified in response to the user""s request. A human user can select a tooth in the graphical representation and, in response, information about the tooth can be displayed. The information can relate to the motion that the tooth will experience while moving along the treatment path. The information can also indicate a linear distance between the tooth and another tooth selected in the graphical representation. The teeth can be rendered at a selected one of multiple viewing orthodontic-specific viewing angles. A user interface through which a human user can provide text-based comments after viewing the graphical representation of the patient""s teeth can be provided. The graphical representation data can be downloaded to a remote computer at which a human view wishes to view the graphical representation. An input signal from a 3D gyroscopic input device controlled by a human user can be applied to alter the orientation of the teeth in the graphical representation.
Advantages of the system may include one or more of the following. The system facilitates automated staging after final setup. The system eliminates manual staging, saves time and is convenient to use. An easy to use graphical user interface supports the entry of treatment planning requirements such as particular staging pattern(s), anchorage requirement(s) (low, mid, high), and the minimum allowable tooth movements.